HasClusterID() and allow-untagged-cloud

[guettli]

Looking at the basic_main.go

	if !cloud.HasClusterID() {
		if config.ComponentConfig.KubeCloudShared.AllowUntaggedCloud {
			klog.Warning("detected a cluster without a ClusterID.  A ClusterID will be required in the future.  Please tag your cluster to avoid any future issues")
		} else {
			klog.Fatalf("no ClusterID found.  A ClusterID is required for the cloud provider to function properly.  This check can be bypassed by setting the allow-untagged-cloud option")
		}
	}

basic_main.go

But where is ClusterID actually used?

Afaik allow-untagged-cloud is deprecated, but afaik ClusterID does not get used.

The current state is confusing.

Please explain how a ccm should implement a ClusterID.